US3659284A

US3659284A - Television gaming apparatus

Info

Publication number: US3659284A
Application number: US828154A
Authority: US
Inventors: William T Rusch
Original assignee: Sanders Associates Inc
Current assignee: Lockheed Martin Corp
Priority date: 1969-05-27
Filing date: 1969-05-27
Publication date: 1972-04-25
Anticipated expiration: 1989-04-25
Also published as: HK48477A; CA993001B; DE2017312A1; CA920160A; IL33915A0; FR2043701B1; FR2043701A1; MY7500260A; CH529491A; IL33915A; GB1318051A; BE751008A; NL152422B; NL7007591A; DE2017312B2; JPS5127965B1; DE2017312C3; GB1319410A; SE364186B

Abstract

Apparatus and methods are herein disclosed for use in conjunction with standard monochrome and color television receivers, for the generation, display and manipulation of symbols or geometric figures upon the screen of the television receivers for the purpose of playing games. The invention comprises in one embodiment a control unit, connecting means and in some applications a television screen overlay mask utilized in conjunction with a standard television receiver. The control unit includes the control means, switches and electronic circuitry for the generation, manipulation and control of video signals which are to be displayed on the television screen. The symbols are generated by developing current pulses proportional to predetermined portions (slices) of horizontal and vertical sawtooth waves. The connecting means couples the video signals to the receiver antenna terminals thereby using existing electronic circuits within the receiver to process and display the signals. An overlay mask which may be removably attached to the television screen may determine the nature of the game to be played. Control units may be provided for each of the participants. Alternatively, games may be carried out in conjunction with background and other pictorial information originated in the television receiver by commercial TV, closed-circuit TV or a CATV station.

Description

United States Patent Rusch .1 A r. 1972 [54] TELEVISION GAMING APPARATUS [57] ABSTRACT [72] Inventor: William T. Rusch, Hollis, NH. Apparatus and methods are herein disclosed for use in conjunction with standard monochrome and color television [73] Asslgnee' Sanders Assocmes Nashua receivers, for the generation, display and manipulation of sym- [22] Filed: May 27, 1969 bols or geometric figures upon the screen of the television receivers for the purpose of playing games. The invention [21] APPLNO 828154 comprises in one embodiment a control unit, connecting means and in some applications a television screen overlay 52 us. Cl. ..340/324 A, l78/6.8,273/85, utilized "J'""E with a standard lelevisim 315/22 315/ I'CCCIVCL The control unit includes the control means, 5 1 1 im. Cl. ..G08b 5/22 switches and cirflwmy f general; mimiPula- [58 1 Field of Search ..340/324 A; 315/22; l78/6.8 and 99 slgnals whlch are be P' Y the television screen. The symbols are generated by develop- [56] References Cited ing current pulses proportional to predetermined portions (slices) of horizontal and vertical sawtooth waves. The con- UNITED STATES PATENTS necting means couples the video signals to the receiver antenna terminals thereby using existing electronic circuits within 2,454,992 12/1948 QOIdSmlIh 6! 3L... ..3l5/22 the receiver to process and p y the g An Overlay 2 g "l' mask which may be removably attached to the television 3'l58'858 l 1x964 Rvans t 320,344 A X screen may determine the nature of the game to be played. e a Control units may be provided for each of the participants Al- 3,249,796 5/1966 M 0fiitt e "315/22 ternatively, games may be carried out in conjunction with 3,497,760 2/l970 Kleslmg ..l78/6.8 X background and other pictorial i f m i originated n the Primary Examiner-David L. Trafton Attorney-Louis Etlinger television receiver by commercial TV, closed-circuit TV or a CATV station.

59 Claims, Drawing Figures HOR. SYNC *|es.5us f' sas as +E swar sAwrboTH 3'63? 1 im lsssus GENERATOR SUCER 3| l WH SPOTI VERT 1l6.66 Ms l-- VIDEO SYNC. MS 34 {4O SIGNAL OR i 37 SPOT I GATE VERTICAL N 9 COINCIDENCE a SYNCi/ o 2 GATE PULSE M SAWTOOTH SPOT l SHAPER GENERATOR VERT. 0

32 SLICER 7 1} e Vi 44 HOR. SYNC $39; 2 43 EQQ' Q SLICIER k SPOT 2 2 COINCIDENCE W 45 GATE VERT.SYNC/ VERT. $122 SLICER PmfmEmPRzsmz $659,284

sum 07 ans TO MULTIVIB(RA)TOR 8| TO MULTI(V| B)RATOR 82 FIGIIB INVENTORV WILLIAM T. RUSCH ATTORNEY PATENTEDAPR25 m2 saw ,12 or 16 V 8| H SYNC/ SAWTOOTH GENS. SPOTI GEN SPOT 2 SEN,

To SPOT 3 GENERATOR POSITION FLIP- FLOP low-0W H TO SPOT! GEN.

FIGI5A To SPOT 3 GENERATOR "HIT" SPOT WITH T55 WALL BOJNCE SYSTEM T g s oTz I C CH 8 vC STRAIGHT STRAIGHT CONTROL CONTROL -JOYSTICK JOYSTICK PLAYER A PLAYER B mvrsw'ron.

V WILLlAM T. RUSCH Arron/ var PATENTEDAPRQS I972 'SHEET I 13 or 16' I58 -||NTEGRATOR HORIZONTAL FLIP FLOP I65 VERTICAL I F LIP- FLOP COMPARATOR 0 A63 coMPARAToRtg GENERAL SYSTEM I59 INTEGRATOR GENERAL SYSTEM j IG. I6A

COINCIDENCE DETECTOR AND CROWBAR FIG WA FIGWB INVENTOR. WILLIAM T. RUSCH "WWI-$4 M PATENTED APR 2 SHEET 1 0F 16 CONVENTIONAL 'f' TELEVISION I95 VERTICAL HORIZONTAL RECEIVER Xwg'OOTH m room V'DEO GENERATOR GENERATOR DETECTOR Q 20 we WI 202 VIDEO g I ep 203R2 AMPLIFIER SPOT! H'GEN. H '94 R REDGATE SUMMER l i PULSESHAPER SPOT n A92 GEN.

Hn Vn SYNC A99 1 I98 SEPARATOR 19s EEWr'SSfH 'fifififl vweo GENERATOR GENERAToR DETECTOR CONVENTIONAL 19s TELEV|S|ON N RECEIVER VIDEO IS! Leg AMPLIFIER -ggg'rl v: 8H

" r 3 QRDGATE PfiLsE SHAPER l -*SPOT 2 GEN.

F IG. l8 B INVENTORE WILLIAM T RUSCH kt-M4. fl m ATTORNEY SHEET .18 0F '16 PATENTEI] APR 2 5 I972 INVENTOR.

WILLIAM T. RUSCH BY g! ATTORNEY A, moEmwzww 16953025 00 Ill cm 42 moEmmzww E0055 B25 TELEVISION *GAMING APPARATUS This invention relates tothe subject matter disclosed in application Ser. No. 126,966 filed Mar. 22, 1971, a continuation of application Ser. No. 697,798 filed Jan. 15, 1968, now abandoned; and application Ser. No. 713,862, filed Mar. 18, 1968, now U.S. Pat. No. 3,497,829.

BACKGROUND OF TI-IE'INVENTION This invention relates to an apparatus and method by means of which standardtelevision receivers can be utilized as active rather than passive instruments. This is accomplished in certain embodiments'by having participants manipulate controls of a control unit connected to the television receiver to cause a symbol, such as a rectangle, circle, ring, star, cross, spot or a plurality of spots, to be displayed upon the television screen by means of which the participants can play a variety of games, participate in simulated training programs, as well as carry out other activities. By way of example, modified versions of the well-known game of ping-pong may be played by two participants by physically or electronically placing an appropriate mask representing the net upon the screen of the television receiver. Three displayed spots represent two paddles and a ball wherein the ball is moved in a particular direction when hit" by a paddle.

Heretofore, color and monochrome television receivers have been used :generally by the home and-other viewers as passive devices; i.e.,"the television receiver is used only as a display means for programming originating at a studio. The viewer is limited 'to selecting the presentations available for viewing-and is not a participant to the extent that he can control or influence the nature of, or add to the presentation displayed on the receiver screen.

A standard receiver employed with auxiliary equipment to provide an active form of home entertainment is described in a patent application for Television Gaming and Training Apparatus, Ser. No. 126,966 filed Mar. 22, 1971 a continuation of Ser. No. 697,798, filed Jan. 15, 1968, and assigned to the assignee of this application. Since most homes are equipped with television receivers, the only expense required to provide added family enjoyment is the expense of a control unit of one type or another.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide apparatus and methods for displaying video signals on the screen of a television receiver, where some or all of the video signals are both generated and controlled by apparatus external to the television receiver.

It is another object of the present invention to provide an apparatus and method wherein a standard color or monochrome television receiver is utilized as an active instrument for playing various types of games involving one or more participants.

It is a further object of the present invention to provide a device whereby an individual may pit his alertness, skill, manual dexterity and visual acuity against automatically controlled video displays.

It is yet a further object of the present invention to provide an apparatus which will generate spots such as squares, rectangles, circles, rings, stars, etc. which may be controlled by one or more participants for playing various types of games.

It is another object of the present invention to provide a cathode ray tube apparatus for displaying symbols to be manipulated by participants.

It is yet another object of the present invention to provide an apparatus which will allow one or more participants to actively use a standard television set while receiving background and other pertinent pictorial information from a cooperative commercial TV, closed-circuit TV, or CATV station, thus combining or alternating studio and home-generated information on the TV screen.

It is still another object of the present invention to allow the use of a standard TV set for gaming or other activities without the need for any kind of internal electrical connection to the TV set for the introduction of video and/or chroma signals, connections being required to be made only to the externally accessible antenna terminals.

In accordance'with one embodiment of the present invention, a television gaming apparatus is provided for generating video signals in accordance with the standardized television format, which signals may be controlled by an individual operator by means of a joystick or other manually operative means. The television gaming apparatus comprises control apparatus having included therein the necessary electronic circuits to produce video signals which are compatible with standard television receivers.

The control apparatus has video signal control means mounted thereon for each access and connecting means are provided for coupling the video signals generated within the control box to the television receiver.

By way of illustration, the television gaming apparatus can be used for playing a game of ping-pong by providing on a TV screen two spots which represent paddles. Means are provided for enabling the players tocontrol the vertical'movement of the spots. Means are also provided for generating on the screen of the television receiver a third spot which represents the ping-pong ball, which spot automatically moves from an off-screen left position to an off-screen right position and vice versa unless hit" by a paddle spot whereupon the ball spot will change direction. The players have further controls for changing the vertical position of the ball spot.

Suitable overlays or presentations from a cooperative TV station may be used in conjunction with said games to enhance the asthetic appeal thereof.

BRIEF DESCRIPTION OF THE DRAWINGS The above-mentioned and other features and objects of this invention will become more apparent by reference to the following description taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a pictorial view illustrating the principle components of an embodiment ofthe invention;

FIG. 1A is a pictorial view illustrating an alternate embodiment for the control unit of FIG. 1;

FIG. 2 is a sketch illustrating a typical TV screen and overlay mask as employed in an embodiment of this invention;

FIG. 3 is a sketch illustrating the manner in which spots are formed on a TV screen;

FIG. 4 is a block diagram illustrating the spot generation;

FIG. 5 is a block diagram of the preferred mode of generating spots on a TV screen;

FIG. 6 is a plurality of sketches illustrating shapes of representative spots;

FIG. 7 is a schematic of a sync/sawtooth generator employed in the embodiment of FIG. 5;

FIG. 8 are schematics of circuits employed in the embodiment ofFIG. 5;

FIG. 9A is a schematic of potentiometer controls used to generate slicer control voltages;

FIG. 9B is a schematic of joystick controlled potentiometers used to generate slicer control voltages;

FIG. 9C is a schematic of joystick controlled potentiometerintegrator control used to generate slicer control voltages;

FIG. 10A is a schematic of a position flip-flop circuit used to control spotsin certain applications of this invention;

FIG. 10B are sketches, of representative waveforms of the circuit of FIG. 10A;

FIG. 11A is a block diagram of apparatus for controlling a hit" spot;

FIG. 11B is a sketch illustrating the manner in which the apparatus of FIG. 1 IA controls a hit" spot; supplies FIG. 11C is a schematic of the horizontal gated differentiator of FIG. 11A;

FIG. 11D is a schematic of the bilateral switch, integrator and wall bounce control of FIG. 11A;

FIG. 12A is a diagram of apparatus for a simulated pingpong game;

FIG. 12B is a sketch of a TV screen illustrating the manner of play of the ping-pong game of FIG. 12A;

FIG. 12C is a sketch of a TV screen illustrating the manner of play of a simulated hockey game using the apparatus of FIG. 12A;

FIG. 12D is a sketch of a TV screen illustrating the manner of play ofa simulated baseball game;

FIG. 13 is a sketch illustrating a class of games (chase" games) which can be played using the apparatus of this inventron;

FIG. 14 is a diagram of apparatus for a simulated hockey game;

FIG. 15A is a diagram ofapparatus for a simulated handball game;

FIG. 15B is a sketch of a TV screen illustrating the manner of play of a simulated handball game using the apparatus of FIG. 15A;

FIG. 16A is a diagram of apparatus for a simulated pinball game;

FIG. 16B is a sketch of a TV screen illustrating the manner of play ofa pinball game using the apparatus ofFlG. 16A;

FIG. 17A is a diagram of apparatus for a simulated bowling game;

FIG. 17B is a sketch of a TV screen illustrating the manner of play ofa bowling game using the apparatus of FIG. 17A;

FIGS. 18A-l8C are block diagrams of built-in embodiments of the invention;

FIG. 19 is a simplified block diagram of another embodiment ofTV gaming apparatus; and j 7 FIG. 20 is an alternate embodiment of circuits employed in the embodiment of FIG. 5.

DESCRIPTION OF PREFERRED EMBODIMENTS The principal components of one embodiment of a television gaming system configured according to the invention are illustrated in FIG. I which is a pictorial view showing a television receiver 10, a control unit 14 and means 12 for connecting control unit 14 to receiver 10. The television receiver 10 employed can be any of the standard commercially available models that are generally used for home entertainment. Either a monochrome or color television set may be used with the present invention since the basic principles of the invention apply to both types. The connection means 12 is in this embodiment a shielded cable, for example, shielded twin lead, and is attached to the antenna terminals of receiver 10 in conventional fashion.

Control unit 14 generates video signals shown as spots 20,, 20 and 21. The spots 20 and 20 are positioned on the receiver screen 18 by

knobs

16,, 17,, and 16 17 respectively. For clarity, the spot 21 is illustrated as a circle and the spots 20 are illustrated as diamonds, however, many shapes can be generated. In the devices to be described hereinafter, circles are generally employed.

Knob 16 controls the vertical position of spot 20 while knob 17 controls the horizontal position thereof. Thus, it can be seen that the spot 20 may be positioned at any point on the screen by the proper manipulation of knobs l6 and 17. Spot 20 is positioned in like manner by

knob

16,, 17,. In this embodiment spot 21 is automatically positioned on screen 18 without manual control. This will be described more fully hereinafter. A reset switch 26 is shown on the control unit 14 and is used to reset the picture on the television screen. For example, a game may be played in which one spot is to be positioned over the other and when this is accomplished one spot will disappear and the background will change color. When games of this nature are played, a reset means is required before play can be resumed. Reset switch 26 performs this function.

A knob 15 controls background color for color TV receiver applications wherein a chroma generator is employed in the manner set forth in said application Ser. No. 126,966. Alternatively, control unit 14 may be broken up into a master control unit containing'the electronic circuits and individual control units containing control knobs 16 17,, and 16 17,, whereby each participant may operate from a position away from the other and so not to interfere with other players. This is illustrated in FIG. 1A wherein control unit 14 is broken up into a master control unit 27 and

individual control units

22 and 23. The master control unit 27 contains the electronic circuitry found in control unit 14 and controls 26 and 15. Knobs l6, l7 and 16,, 17 which position the spots 20, and 20 are situated on

individual control units

22 and 23 respectively.

The knobs l6, 17 may be combined into a single joystick permitting control of the horizontal and vertical spot positioning by a single control means.

Other spot position control means (not shown) can be incorporated into the control unit(s) and these will be described hereinafter.

Rather than provide a separate control unit, the electronic circuitry of the control unit could be built into the television receiver as a constituent part thereof and the receiver sold as both an active and passive home entertainment system. Controlunits containing the actual manipulating controls can be provided as above.

A typical sequence of steps to play a game using the present invention would be as follows: 1. Attach connection means 12 to TV set 10 at the antenna terminals thereof, if not already attached; 2. turn the TV set on: 3. select the proper channel on the set for the control unit being used; 4. apply power to the control unit; 5. attach a mask on the face of the TV screen; if required for the game to be played; 6. begin the game.

Referring now to FIG. 2, a television screen 18 is illustrated having three spots 24,, 24,, and 25 displayed thereon. Spots 24 are hitting spots and spot 25 is a hit" spot. Spots 24 and 24 represent, for example, hockey players while spot 25 represents a hockey puck. An overlay mask 30 of some type of transparent material such as plastic or the like, having some type of pattem, picture or other illustration pertaining to the particular game to be played is shown in a lifted position. Prior to engaging in a game, the overlay mask 30 is temporarily attached to television screen 18 and in such close proximity to it as not to create any distortion when viewed with reference to spots 24 and 25. One type of overlay mask represents a hockey field to be used for playing a modified game of hockey. Still another pattern could represent a ping-pong table, baseball diamond, etc. These are but a few of the many type games that can be adapted for use with the present invention.

Alternatively, rather than employ overlay mask 30, the pat tern to be provided could be displayed directly on the screen 18. The pattern could be broadcast by TV stations or alternatively could be sent to a non-used channel over closed-circuit or CATV lines. It could also be generated electronically in the video control system.

The basic theory of TV gaming devices as described herein is now set forth.

Referring to FIG. 3, at time zero the TV electron beam is at the upper left of screen 18. It starts moving quickly to the right and slowly downwards. Sixty-three and one-half (63 .5) microseconds later a 5 microsecond horizontal sync pulse is fed into the TV set, causing the beam to fly back rapidly to the left 'of the screen. The beam then moves to the right for 63.5 microseconds until the next horizontal sync pulse causes the next flyback to the left. After about 250 such horizontal scans (lines) the beam has progressed to the bottom of the screen. A vertical sync pulse fed into the TV set causes rapid (I millisecond) vertical flyback to the top of the screen and another cycle begins.

Now, still referring to FIG. 3, assume that the major portion of the screen is dark (beam blanked) except for the areas shown as SPOT 1 and SPOT 2. The spots are made by passing a (positive) unblanking video signal to the TV set when. and

only when, the beam is passing over the areas of the spots. (Quotes are used around beam because although there is no real beam when blanking is in effect, the scanning signals occur and can be thought of as still moving the non-existent beam" in the scanning pattern).

The video (unblanking) signals required for spot generation are described with the aid of FIG. 3. To derive SPOT 1, assume that a pulse of width W is generated T microseconds after the occurrence of each horizontal sync pulse. Define these new pulses as P horizontal video pulse for SPOT 1. If these P, pulses were used as unblanking (video) in the TV set, the beam would brighten whenever it had moved a distance equivalent to T from the left side of the screen. If would stay bright for a length equivalent to W and then darken. This would happen all during the vertical scan and 250 bright little line segments of width W would appear to the eye as a vertical column (shown shaded in FIG. 3).

Now, SPOT 1 vertical video pulses P are made to be of width W and to occur T milliseconds after the start of the vertical sweep. W is on the order of 63.5 microseconds, permitting some horizontal scans to take place while P is on. If P were used alone as the unblanking (video) signal to the TV set, ten lines the width of the set would be brightened while P was on and a bright horizontal bar of width W (shown shaded in FIG; 3) would be viewed.

As the last step in spot generation, SPOT 1 horizontal video pulses (P and vertical video pulses (P are passed through a coincidence gate. The gate has anoutput only when both P and P are on. The gate output becomes SPOT 1 video (unblank) signal. From FIG. 3 it is obvious that the beam is now unblanked only where the P, vertical shaded column and the P horizontal shaded bar overlap. Thus, a bright spot SPOT 1, comprised of about 10 small line segments, each W wide, is developed. SPOT 2 is developed in the like manner.

FIGS. 4 and 5 are block diagrams illustrating the manner in which the signals discussed with respect to FIG. 3 are generated.

The timing for the television gaming system is established by a horizontal sync/sawtooth generator 31 and a vertical sync/sawtooth generator 32. The horizontal sync/sawtooth generator 31 generates a series of negative horizontal sync pulses 33 having a repetition rate equivalent to the standard horizontal scanning frequency used in United States commer cial television receivers and the vertical sync/sawtooth generator generates a series of negative vertical sync pulses 34.

The vertical sync/sawtooth generator 31 also generates a 15.75 KHz sawtooth wave 35 (refer now to FIG. 5). Sawtooth wave 35 has end limits of +E and 0. It is directly coupled to a SPOT 1 horizontal slicer 36. A slice of the sawtooth ramp of length W is passed through the slicer. By varying voltage e delay T can be varied for spot positioning from left to right of the TV screen.

A 60Hz sawtooth 37 is generated by vertical sync/sawtooth generator 32 and is similarly sliced in a SPOT 1 vertical slicer 29, to give ramp width W, and voltage controlled delay T The two sliced waves are differentiated by

capacitors

38 and 39 which connect to the low input impedance of a SPOT 1 coincidence gate 40. Since thecurrent through a capacitor is C de/dt, current pulses appear only during the ramp portions of the sliced waveforms. Although the slope of the vertical ramp is only about one two hundred and sixtieth times that of the horizontal ramp (60 Hz] 15,750 Hz), by making capacitor 39 approximately 260 times the value of capacitor 38, current pulses i,,, and i are made equal in magnitude. Both i and i must be present to exceed in magnitude the (negative) threshold of the gate thus producing the SPOT 1 video signal.

If the invention is to be employed in conjunction with TV systems having different frequencies (number of horizontal lines and vertical flyback) then the vertical and horizontal sync/sawtooth generators would be constructed at the different frequencies. This would be particularly applicable in conjunction with foreign (other than U.S.) TV systems.

Other spots are generated in similar fashion. For example, SPOT '2 horizontal slicer 41 is also coupled to the horizontal sync/sawtooth generator 31 and SPOT 2 vertical slicer 42 is also coupled to vertical sync/sawtooth generator 32. The horizontal and

vertical slicers

41 and 42 are coupled to a SPOT 2 coincidence gate 43 by capacitors 44 and 45, respectively. All video spot signals are fed to an OR gate and pulse shaper 46. The OR gate prevents excessive brightening when spots are positioned on top of one another. The pulse shaper is required because in the present embodiment 6 volt sawtooth waveforms are used. With such low voltage the slicing action is soft (rounding at beginning and end of ramp slice). Consequently, the current pulses produced by differentiation of the ramp slicers are rounded pulses. Without shaping they produce a spot without sharply defined edges the edges just fade out" gradually into the dark background. The summer modulater and RF oscillator 28 are set forth in said patent application Ser. No. 126,966. The RF signal presented to the antenna terminals is detected and processed by the TV receiver in the standard manner and displayed on the screen thereof. The output from OR gate and pulse shaper 46 is applied to a summer which sums all the signals presented thereto (including sync pulses from the horizontal and vertical sync/sawtooth generators, outputs from chroma generator, if used, etc.). This forms the composite video signal. This signal is applied to a modulator and RF oscillator for modulating the video informationwith the RF oscillator carrier to generate the requisite modulated RF signal which is coupled to the TV antenna terminals.

One of the objects of the present invention is a system to produce a round spot which in some instances is more pleasant and interesting than a square or rectangular spot, (especially for ball" games like ping-pong, baseball, etc.). This is achieved (even with the pulse shaper which just gives the round spot sharply defined edges) by the rounded edges" of the current pulses going into the coincidence gate. For example, the leading and trailing edges of current pulse i are rounded. Thus any i pulses which are added to i at this time will have thinner portions protruding below the gate threshold level than those appearing during the full amplitude middle of i Subsequent pulse shaping of the pulses which get past the gate threshold steepens their sides (for sharp spot edges) but doesn't change their width. Thus the spot is narrower at top and bottom than it is in the middle.

Some of the various spot shapes which can be generated are shown in FIG. 6. Spots a, b and c are generated simplyby varying the coincidence gate threshold 53. (For an individual spot. Or, all spots can be made to change shape together by changing the amplitude and slope of the common sawtooth generators.)

Spots d and e are made either by changing sawtooth slope (thus changing W and w or by changing the slice am plitude (again changing W and W Various other shapes (four pointed star, cross, etc.) can be generated by simple adjustments of various component values or voltages and by switching. All spots can be made hollow as described hereinafter.

Referring now to FIG. 7, there is illustrated thereby schematically one embodiment of the sync/sawtooth generators. A generator of this type is described in detail in my co-pending patent application for Linear Sawtooth Generator" Ser. No. 713,862, filed Mar. 1 8, 1968, now U.S. Pat. No. 3,497,829.

The SPOT 1

slicers

36, 29, the SPOT 1 coincidence gate 40 and the OR gate and pulse shaper 46 are illustrated schematically in FIG. 8. The horizontal 15.75 Hz sawtooth waveform 35 and the vertical 60 Hz sawtooth wave 37 waveform are sliced in the

slicers

36 and 29, respectively. The slicers comprise means for generating a predetermined slice of the sawtooth waveforms and in the present embodiment include back-to-

back diodes

47, 48, and 49, 50, respectively. The input sawtooth waveforms are applied to one side of the diode pair, with the other side being capacitively coupled via

capacitors

51, 52, respectively to ground and being supplied voltages

Claims

1. In combination with a standard television receiver, apparatus for generating signals representing a symbol to be displayed on the screen of said television receiver, comprising: means for generating sync signals; means for generating a first sawtooth wave; means for generating a second sawtooth wave; means coupled to said first sawtooth wave generating means for generating first current pulses proportional to a predetermined slice of said first sawtooth wave; including a first slicer having first and second diodes connected back-to-back with one junction thereof coupled to said first sawtooth wave generating means, a capacitor coupled from the other junction to ground and means for receiving a control signal at said other junction, and first means for differentiating the output from said first slicer; means coupled to said second sawtooth wave generating means for generating second current pulses proportional to a predetermined slice of said second sawtooth wave; including a second slicer having third and fourth diodes connected back-toback with one junction thereof coupled to said second sawtooth wave generating means, a capacitor coupled from the other junction to ground and means for receiving a control signal at said other junction, and second means for differentiating the output from said second slicer; a coincidence gate coupled to said first and second current pulse generating means; means for summing the output from said coincidence gate and said sync signals; an RF oscillator; means for modulating the output of said RF oscillator with said summed signal; and means for applying said modulated signal to said receiver.

2. Apparatus as defined in claim 1 wherein said first and second differentiating means includes: a first capacitor coupled from said first slicer to said coincidence gate; and a second capacitor coupled from said second slicer to said coincidence gate.

3. Apparatus as defined in claim 1 wherein said coincidence gate includes: a transistor having first, second and third electrodes, said third electrode being coupled to ground, with the output of said coincidence gate obtained at said third electrode; a voltage source; a first resistor coupled from said second electrode to said voltage source; a second resistor coupled from said second electrode to ground; and a third resistor coupled from said third electrode to said voltage source.

4. Apparatus as defined in claim 3 wherein said second resistor is a variable resistor which adjusts the threshold of said coincidence gate and thereby symbol size and shape.

5. Apparatus as defined in claim 4, further including means for generating first and second control signals which determine said predetermined slices, said control signals being coupled to said first and second slicers.

6. Apparatus as defined in claim 5 wherein said first and second control signal generating means includes: first and second voltage source; a first potentiometer coupled across said first voltage source, the arm of said potentiometer being electrically coupled to said first slicer; a second potentiometer coupled across said second voltage source, the arm of said potentiometer being electrically coupled to said second slicer; aNd means for adjusting the position of said arms to thereby vary said control signals.

7. Apparatus as defined in claim 6 wherein said adjusting means includes: a first knob coupled to said arm of said first potentiometer; and a second knob coupled to said arm of said second potentiometer.

8. Apparatus as defined in claim 6 wherein said adjusting means includes a joystick coupled to both arms of said potentiometers.

9. In combination with a standard television receiver, apparatus for generating signals representing a symbol to be displayed on the screen of said television receiver, comprising: a control unit including means for generating horizontal and vertical signals representing the symbol to be displayed, means for synchronizing a television raster scan, and means for manipulating the position of the symbol on the screen, said manipulating means including means for generating first and second control signals coupled to said means for generating horizontal and vertical signals, said control signal generating means including means for causing the displayed symbol to travel back and forth between two predetermined positions off-screen; and means for electrically coupling said control unit to said television receiver.

10. In combination with a standard television receiver, apparatus for generating signals representing a symbol to be displayed on the screen of said television receiver comprising: a control unit including means for generating horizontal and vertical signals representing the symbol to be displayed, means for synchronizing a television raster scan, and means for manipulating the position of the symbol on the screen, said manipulating means including means for generating first and second control signals coupled to said means for generating horizontal and vertical signals, said control signal generating means including means for causing the displayed symbol to travel back and forth between two predetermined positions; and means for electrically coupling said control unit to said television receiver; wherein said means for causing said displayed symbol to travel between two predetermined positions includes: a bistable multivibrator having at least a first input and first and second outputs; a first resistor; a first diode, the anode thereof being coupled to one side of said first resistor with the cathode thereof being coupled to the first output of said bistable multivibrator; a second diode, the cathode thereof being coupled to the other side of said first resistor with the anode thereof being coupled to said second output of said bistable multivibrator; a second resistor; a third diode, the cathode thereof being coupled to one side of said second resistor with the anode thereof being coupled to the first output of said bistable multivibrator; a fourth diode, the anode thereof being coupled to the other side of said second resistor with the cathode thereof being coupled to said second output of said bistable multivibrator; a third resistor; a fifth diode, the anode thereof being coupled to one side of said third resistor with the cathode thereof being coupled to the first output of said bistable multivibrator; a sixth diode, the cathode thereof being coupled to the other side of said third resistor with the anode thereof being coupled to said second output of said bistable multivibrator; a fourth resistor; a seventh diode, the cathode thereof being coupled to one side of said fourth resistor with the anode thereof being coupled to the first output of said bistable multivibrator; an eighth diode, the anode thereof being coupled to the other side of said fourth resistor with the cathode thereof being coupled to the second output of said bistable multivibrator; means for applying triggering pulses to said first input of said bistable multivibrator; means coupling said third and fourth resistors for providing a first control siGnal; and means coupling said first and second resistors for providing a second control signal.

11. Apparatus as defined in claim 10 wherein said trigger applying means includes a slow free-running bistable multivibrator.

12. Apparatus as defined in claim 11 wherein the output from said slow free-running bistable multivibrator is also applied to a second input of said bistable multivibrator.

13. Apparatus as defined in claim 10 wherein said resistors are variable.

14. Apparatus as defined in claim 10, further including: a first RC network coupled to said means coupling said first and second resistors; and a second RC network coupled to said means coupling said third and fourth resistors.

15. Apparatus as defined in claim 10, further including: a first integrator coupled to said means coupling said first and second resistors; and a second integrator coupled to said means coupling said third and fourth resistors.

16. Apparatus as defined in claim 5 wherein said first and second control generating means includes means for generating a first sinusoid and a second sinusoid phase displaced from said first sinusoid whereby the symbol will traverse a path such as a circle, ellipse ''''figure eight'''' etc.

17. Apparatus for generating signals representing a ''''hitting'''' symbol and a ''''hit'''' symbol to be displayed on the screen of a television receiver, comprising: means for synchronizing a television raster scan; means for generating electrical signals representing a hitting symbol; means coupled to said means for generating signals representing a hitting symbol for generating first and second control signals to vary the horizontal and vertical positions of said hitting symbol; means for ascertaining coincidence between a hitting symbol and a hit symbol; first means for differentiating a portion of the signal output of said first control signal generating means upon coincidence between said hitting symbol and said hit symbol; second means for differentiating a portion of the signal output of said second control signal generating means upon coincidence between said hitting symbol and said hit symbol; first means for integrating said first differentiated signal for providing a first hit symbol control voltage; second means for integrating said second differentiated signal and for providing a second hit symbol control voltage; a hit symbol generator having as control inputs thereto said first and second hit symbol control voltages whereby said hit symbol moves with a velocity proportional to the velocity of a hitting when coincident therewith.

18. Apparatus as defined in claim 17 further including first and second RC delay circuits coupled to said first and second differentiating means, respectively.

19. Apparatus as defined in claim 18, further including means for reversing the polarity of said first and second hit symbol control voltages when the outputs of said first and second integrators reach at least a first predetermined voltage level.

20. Apparatus as defined in claim 19 wherein said polarity reversing means, includes: a first and second comparators coupled to the outputs of said first and second integrators, respectively; means for applying reference signals to said first and second comparators; and means for reversing the polarity of the outputs of said differentiators responsive to outputs of said comparators.

21. Apparatus as defined in claim 20, further including first and second bistable multivibrators coupled to said first and second comparators, respectively, the outputs of said bistable multivibrators signifying the desired relative polarity of said integrator outputs.

22. In combination with a standard television receiver, apparatus for generating signals representing a first and second hitting symbol and a hit symbol to be displayed on the screen of said television receiver, comprising: means for generating sync signAls; means for generating a first sawtooth wave; means for generating a second sawtooth wave; a first hitting symbol generator; a second hitting symbol generator; a hit symbol generator; means for applying said first and second sawtooth waves to said symbol generators; means for generating first and second control signals for said first hitting symbol generator; means for coupling said first and second control signals to said first hitting symbol generator; means for generating third and fourth control signals for said second hitting symbol generator; means for coupling said third and fourth control signals to said second hitting symbol generator; means for generating fifth and sixth control signals for said hit symbol generator; means for coupling said fifth and sixth control signals to said hit symbol generator; means for coupling said first, second, third, and fourth control signals to said means for generating fifth and sixth control signals; and means for coupling the outputs of said symbol generators and said sync signals to the television receiver.

23. Apparatus as defined in claim 22 wherein said means for generating fifth and sixth control signals includes: first means for detecting coincidence between said first hit symbol and said hitting symbol; second means for detecting coincidence between said second hit symbol and said hitting symbol; a first monostable multivibrator coupled to said first coincidence means; a second monostable multivibrator coupled to said second coincidence means; first, second, third, and fourth gates having as inputs thereto said first, third, second, and fourth control signals, respectively; means for coupling the output of said first monostable multivibrator to said first and third gates; means for coupling the output of said second multivibrator to said second and fourth gates; a first differentiator coupled to said first and second gates; a second differentiator coupled to said third and fourth gates; first sampling means coupled to said first differentiator; second sampling means coupled to said second differentiator; first and second OR gates, the outputs thereof being coupled to said first and second sampling means, respectively, the inputs thereof being coupled to both said monostable multivibrators; first and second peak detectors coupled to said first and second sampling means, respectively; and first and second integrators coupled to said first and second peak detectors, respectively, said fifth and sixth control signals being derived at the outputs of said first and second integrators, respectively.

24. Apparatus as defined in claim 23, further including: third and fourth OR gates, each coupled to both said monostable multivibrators; a first and second bistable multivibrator, each having first and second inputs, said first inputs taken at the outputs of said third and fourth OR gates, respectively; a first and second comparator, the outputs thereof being coupled to second inputs of said first and second bistable multivibrators, respectively; said first and second comparators being coupled to said first and second integrators, respectively; means for generating reference voltages; means for applying said reference voltages to said comparators; and first and second means for reversing the polarity of the outputs of said peak detectors, said polarity reversing means coupled to the outputs of said first and second bistable multivibrators, respectively.

25. In combination with a standard television receiver, apparatus for generating symbols upon the screen of the receiver to be manipulated by at least one participant, comprising: means for generating a hitting symbol, and means for generating a hit symbol including means for ascertaining coincidence between said hitting symbol and said hit symbol and means for imparting a distincT motion to said hit symbol upon coincidence.

26. The combination of claim 25 wherein said means for generating a hitting symbol includes means for providing horizontal and vertical control signals for varying the horizontal and vertical positions of said hitting symbol.

27. The combination of claim 26 wherein said means for providing horizontal control signals includes a voltage source, a potentiometer coupled across said voltage source and an integrator coupled to the arm of said potentiometer, said control signal being derived at the output of said integrator.

28. The combination of claim 25 wherein said means for generating a hit symbol includes means for providing horizontal and vertical control signals for varying the horizontal and vertical positions of said hit symbol.

29. The combination of claim 28 wherein said means for providing horizontal control signals for said hit symbol includes means for causing said hit symbol to move back and forth across the screen when triggered.

30. The combination of claim 29 wherein said triggering means includes a slow free-running multivibrator.

31. The combination of claim 29 further including means for detecting coincidence between a hit symbol and a hitting symbol and means for causing said hit symbol to change direction upon coincidence.

32. The combination of claim 25 wherein said means for generating a hit symbol further includes means for causing said hit symbol to move away from a predetermined position of the screen with a reflection angle equal to the incident angle at which said hit symbol approached said predetermined position.

33. In combination with a standard television receiver, apparatus for generating signals representing a symbol to be displayed on the screen of said television receiver, comprising: means for generating sync signals; means for generating a first sawtooth wave; means for generating a second sawtooth wave; means coupled to said first sawtooth wave generating means for generating first current pulses proportional to a predetermined slice of said first sawtooth wave; including a first slicer having first and second diodes connected back-to-back with one junction thereof coupled to said first sawtooth wave generating means, a capacitor coupled from the other junction to ground and means for receiving a control signal at said other junction, and first means for differentiating the output from said first slicer; means coupled to said second sawtooth wave generating means for generating second current pulses proportional to a predetermined slice of said second sawtooth wave; including a second slicer having third and fourth diodes connected back-to-back with one junction thereof coupled to said second sawtooth wave generating means, a capacitor coupled from the other junction to ground and means for receiving a control signal at said other junction and second means for differentiating the output from said second slicer; a coincidence gate coupled to said first and second current pulse generating means; means for summing the output from said coincidence gate and sync signals; means for applying the output of said summing means to the video and sync circuits of said television receiver.

34. Apparatus as defined in claim 33, further including means for disconnecting the video detector of said television receiver from said video amplifier.

35. In combination with a standard television receiver, apparatus for generating signals representing a first and second hitting symbol and a hit symbol to be displayed on the screen of said television receiver, comprising: means for generating a first sawtooth wave; means for generating a second sawtooth wave; a first hitting symbol generator; a second hitting symbol generator; a hit symbol generator; means for applying said first and second sawtooth waves to said symbol generators; means for generating first and second control signals for said first hitting generator; mEans for coupling said first and second control signals to said first hitting symbol generator for changing the position thereof; means for generating third and fourth control signals for said second hitting symbol generator; means for coupling said third and fourth control signals to said second hitting symbol generator for changing the position thereof; means for applying the output of said spot generator to the video amplifier of said television receiver.

36. In combination with a conventional television receiver, apparatus for generating signals representing a symbol to be displayed on the screen of said television receiver, comprising: means for generating vertical and horizontal sawtooth waveforms; means for synchronizing said vertical and horizontal sawtooth waveforms to the sync signals received in said television receiver from a broadcast signal; a spot generator including a first slicer having first and second diodes connected back-to-back with one junction thereof coupled to said vertical sawtooth generating means, a capacitor coupled from the other junction to ground and means for receiving a first control signal at said other junction, and first means for differentiating the output from said first slicer, and a second slicer having third and fourth diodes connected back-to-back with one junction thereof coupled to said horizontal sawtooth generating means, a capacitor coupled form the other junction to ground and means for receiving a second control signal at said other junction, and second means for differentiating the output from said second slicer, and a coincidence gate coupled to said first and second differentials; and means for applying the output of said spot generator to the video amplifier of said television receiver.

37. The combination of claim 36, wherein said means for generating vertical and horizontal sawtooth waveforms includes means coupled to the horizontal and vertical deflection circuits of said television receiver.

38. Apparatus for generating symbols upon the screen of a cathode ray tube, comprising: a cathode ray tube; means for generating horizontal and vertical sync signals; means for generating first and second sawtooth waves; means for generating a video signal proportional to predetermined slices of said sawtooth waves including a first slicer having first and second diodes connected back-to-back with one junction thereof coupled to said vertical sawtooth generating means, a capacitor coupled from the other junction to ground and means for receiving a first control signal at said other junction, and first means for differentiating the output from said first slicer, and a second slicer having third and fourth diodes connected back-to-back with one junction thereof coupled to said horizontal sawtooth generating means, a capacitor coupled from the other junction to ground and means for receiving a second control signal at said other junction, and second means for differentiating the output from said second slicer, and a coincidence gate coupled to said first and second differentials; a horizontal deflection circuit coupled to said cathode ray tube; a vertical deflection coupled to said cathode ray tube circuit; means for coupling said video signal to the intensity input of said cathode ray tube; means for coupling said horizontal sync signals to said horizontal deflection circuits; and means for coupling said vertical sync signals to said vertical deflection circuit.

39. Apparatus as defined in claim 38, further including means for supplying high voltage to said cathode ray tube.

40. Apparatus as defined in claim 39 wherein said video signal coupling means includes a video amplifier.

42. The apparatus of claim 41 further including means for causing said hit spot to move on-screen subsequent to said hit spot moving off-screen occurring when said hit spot does not make coincidence with one of said hitting spots when in vertical alignment therewith.

43. Apparatus for playing a gun ping-pong type game on the screen of a cathode ray tube, comprising: means for generating a hit spot; a first light sensitive gun; a second light sensitive gun; means for causing said hit spot to move from an off-screen right to an off-screen left position and vice versa; means for causing said hit spot to change direction when one of said light guns receives a pulse of light energy from said hit spot; and means for serving said hit spot when said hit spot goes off-screen.

44. Apparatus for playing a baseball type game on the screen of a cathode ray tube, comprising: means for displaying a hit spot; means for displaying a hitting spot; means for adjusting the vertical position of said hitting spot; means for serving said hit spot; and means for varying the vertical position of said hit spot; and means for denoting coincidence between said hit and said hitting spot whereby said hit spot will reverse directions.

44. Apparatus for playing ping-pong type games by displaying and manipulating symbols on the screen of a cathode ray tube, comprising: means for generating a first hitting spot; means for generating a second hitting spot; means for generatIng a hit spot; means for changing the vertical position of said first hitting spot; means for changing the vertical position of said second hitting spot; means for causing said hit spot to move from an off-screen left position to an off-screen right position and vice versa; means for changing said off-screen right and off-screen left positions; means for denoting coincidence between said first hitting spot and said hit spot; means for denoting coincidence between said second hitting spot and said hit spot; means for causing said hit spot to change horizontal direction upon coincidence between said hit spot and either of said hitting spots; and means for displaying said spots upon the screen of said cathode ray tube.

45. Apparatus for playing a hockey type game upon the screen of a cathode ray tube, comprising: means for displaying a first hitting spot; means for displaying a second hitting spot; means for displaying a hit spot; means for controlling the position of said first and second hitting spots; means for controlling the position of said hit spot including means for ascertaining coincidence between either of said hitting spots and said hit spot and means for imparting a distinct motion to said hit spot upon coincidence.

46. Apparatus as defined in claim 45 wherein said means for controlling said hit spot includes means for causing said hit spot to move in the direction hit by a hitting spot and means for causing said hit spot to bounce away from the sides of said cathode ray tube when coincident therewith.

47. Apparatus for playing a simulated handball game upon the screen of a cathode ray tube, comprising: means for displaying a first symbol representing a first player; means for displaying a second symbol representing a second player; and means for displaying a third symbol representing a ball; means for controlling the position of said first symbol on said cathode ray tube; means for controlling the position of said second symbol on said cathode ray tube; means for controlling the position of said third symbol on said cathode ray tube; said means for controlling the position of said third symbol on said cathode ray tube including means for causing said third symbol to change direction upon coincidence between either of said first or second symbols and means for causing said third symbol to bounce off three of said four sides of said cathode ray tube upon coincidence therewith and to go off-screen when coincident with said fourth side of said cathode ray tube; and means for serving said third symbol when it goes off-screen at said fourth side of said cathode ray tube.

48. Apparatus for generating signals representing a symbol to be displayed on the screen of a television receiver, comprising: means for generating sync signals; means for generating a first sawtooth wave; means for generating a second sawtooth wave; means coupled to said first sawtooth wave generating means for generating first current pulses proportional to a predetermined slice of said first sawtooth wave including a first slicer having first and second diodes connected back-to-back with one junction thereof coupled to said first sawtooth wave generating means, a capacitor coupled from the other junction to ground and means for receiving a control signal to said other junction, and first means for differentiating the output from said first slicer; means coupled to said second sawtooth wave generating means for generating second current pulses proportional to a predetermined slice of said second sawtooth wave including a second slicer having third and fourth diodes connected back-to-back with one junction thereof coupled to said second sawtooth wave generating means, a capacitor coupled from the other junction to ground and means for receiving a control signal at said other junction, and second means for differentiating the output from said second slicer; a coincidence gate coupled to said first and second current pulse generating means; means for coupling the output from said coincidence gate and said sync signals to a television receiver.

49. Apparatus for generating signals representing a hitting symbol and a hit symbol to be displayed on the screen of a television receiver, comprising: means for generating synchronizing signals; means for generating electrical signals representing a hitting symbol; means coupled to said means for generating electrical signals representing a hitting symbol for generating first and second control signals to vary the horizontal and vertical positions of said hitting symbol; first means for differentiating a portion of the signal output of said first control signal generating means; second means for differentiating a portion of the signal output of said second control signal generating means; first means for integrating said first differentiated signal for providing a first hit symbol control voltage; second means for integrating said second differentiated signal and for providing a second hit symbol control voltage; and a symbol generator having as control inputs thereto said first and second hit symbol control voltages whereby said hit symbol moves with a velocity proportional to the velocity of said hitting symbol when coincident therewith.

50. Apparatus for generating signals representing a first and second hitting symbol and a hit symbol to be displayed on the screen of a television receiver, comprising: means for generating sync signals; means for generating a first sawtooth wave; means for generating a second sawtooth wave; a first hitting symbol generator; a second hitting symbol generator; a hit symbol generator; means for applying said first and second sawtooth waves to said symbol generators; means for generating first and second control signals for said first hitting symbol generator; means for coupling said first and second control signals to said first hitting symbol generator; means for generating third and fourth control signals for said second hitting symbol generator; means for coupling said third and fourth control signals to said second hitting symbol generator; means for generating fifth an sixth control signals for said hit symbol generator; means for coupling said fifth and sixth control signals to said hit symbol generator; means for coupling said first, second, third, and fourth control signals to said means for generating fifth and sixth control signals; and means for coupling the outputs of said symbol generators and said sync signals to a television receiVer.

51. Apparatus for generating symbols upon the screen of a television receiver to be manipulated by at least one participant, comprising: means for generating a hitting symbol; and means for generating a hit symbol including means for ascertaining coincidence between said hitting symbol and said hit symbol and means for imparting a distinct motion to said hit symbol upon coincidence.

52. The combination of claim 51 wherein said means for generating a hitting symbol includes means for providing horizontal and vertical control signals for varying the horizontal and vertical positions of said hitting symbol.

53. The combination of claim 52 wherein said means for providing horizontal control signals includes a voltage source, a potentiometer coupled across said voltage source and an integrator coupled to the arm of said integrator, said control being derived at the output of said integrator.

54. The combination of claim 51 wherein said means for generating a hit symbol includes means for providing horizontal and vertical control signals for varying the horizontal and vertical positions of said hit symbol.

55. The combination of claim 54 wherein said means for providing horizontal control signals for said hit symbol includes means for causing said hit symbol to move back and forth across the screen.

56. The combination of claim 55 wherein said means for causing said hit symbol to move back and forth across the screen includes a slow free-running multivibrator.

57. The combination of claim 55 further including means for detecting coincidence between a hit symbol and a hitting symbol and means for causing said hit symbol to change direction upon coincidence.

58. Apparatus for generating signals representing a symbol to be displayed on the screen of a television receiver, comprising: means for generating sync signals; means for generating a horizontal sawtooth wave; means for generating a vertical sawtooth wave; means coupled to said horizontal sawtooth wave generating means for generating first current pulses proportional to a predetermined slice of said horizontal sawtooth wave including a first slicer having first and second diodes connected back-to-back with one junction thereof coupled to said horizontal sawtooth wave generating means, a capacitor coupled from the other junction to ground and means for receiving a control signal at said other junction, and first means for differentiating the output from said first slicer; means coupled to said vertical sawtooth wave generating means for generating second current pulses proportional to a predetermined slice of said vertical sawtooth wave including a second slicer having third and fourth diodes connected back-to-back with one junction thereof coupled to said vertical sawtooth wave generating means, a capacitor coupled from the other junction to ground and means for receiving a control signal at said other junction and second means for differentiating the output from said second slicer; a coincidence gate coupled to said first and second current pulse generating means; means for summing the output from said coincidence gate and sync signals; means for applying the output of said summing means to the video amplifier of a television receiver.

59. Apparatus for generating signals representing a first and second hitting symbol and a hit symbol to be displayed on the screen of a television receiver, comprising; means for generating a first sawtooth wave; means for generating a second sawtooth wave; a first hitting symbol generator; a second hitting symbol generator; a hit symbol generator; means for applying said first and second sawtooth waves to said symbol generators; means for generating first and second control signals for said first hitting symbol generator; means for coupling said first and second control signals to said first hitting symbol generator; means for generating third and fourth control signals for said second hitting symbol generator; means for coupling said third and fourth control signals to said second hitting symbol generator; means for generating fifth and sixth control signals for said hit symbol generator; means for coupling said fifth and sixth control signals to said hit symbol generator; means for coupling said first, second, third, and fourth control signals to said means for generating fifth and sixth control signals; and means for coupling the outputs of said symbol generators to the video amplifier of a television receiver.